[PATCH] net: phy: microchip_t1: fix NULL pointer dereference in lan887x_phy_init()

[huhai <15815827059@163.com>]

From: huhai <huhai@kylinos.cn>

mchp_rds_ptp_probe() may return NULL when CONFIG_PTP_1588_CLOCK is disabled.
lan887x_phy_init() only checks for an error pointer before using the returned
clock to configure the periodic output pin, which can result in a NULL
pointer dereference.

Handle the NULL return as PTP being unavailable and skip the event pin
configuration in that case.

Fixes: 8541fc12edcd ("net: phy: microchip_t1: Enable pin out specific to lan887x phy for PEROUT signal")
Signed-off-by: huhai <huhai@kylinos.cn>
---
 drivers/net/phy/microchip_t1.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/net/phy/microchip_t1.c b/drivers/net/phy/microchip_t1.c
index 3292b2235c8f..e38d20bf6aa4 100644
--- a/drivers/net/phy/microchip_t1.c
+++ b/drivers/net/phy/microchip_t1.c
@@ -1285,14 +1285,16 @@ static int lan887x_phy_init(struct phy_device *phydev)
 		if (IS_ERR(priv->clock))
 			return PTR_ERR(priv->clock);
 
-		/* Enable pin mux for EVT */
-		phy_modify_mmd(phydev, MDIO_MMD_VEND1,
-			       LAN887X_MX_CHIP_TOP_REG_CONTROL1,
-			       LAN887X_MX_CHIP_TOP_REG_CONTROL1_EVT_EN,
-			       LAN887X_MX_CHIP_TOP_REG_CONTROL1_EVT_EN);
-
-		/* Initialize pin numbers specific to PEROUT */
-		priv->clock->event_pin = 3;
+		if (priv->clock) {
+			/* Enable pin mux for EVT */
+			phy_modify_mmd(phydev, MDIO_MMD_VEND1,
+				       LAN887X_MX_CHIP_TOP_REG_CONTROL1,
+				       LAN887X_MX_CHIP_TOP_REG_CONTROL1_EVT_EN,
+				       LAN887X_MX_CHIP_TOP_REG_CONTROL1_EVT_EN);
+
+			/* Initialize pin numbers specific to PEROUT */
+			priv->clock->event_pin = 3;
+		}
 
 		priv->init_done = true;
 	}
-- 
2.40.1